Canadian copper producer First Quantum Minerals Ltd. faces the threat of a strike at its flagship mine in Panama this weekend if union leaders and company representatives can’t agree on a wage contract for workers at the massive operation.

Negotiators are in the final day of salary talks with workers at the Cobre Panama mine, but are “stuck” on some of the details related to wage adjustment and bonuses, union leader Michael Camacho said Friday in text messages. He said a strike will begin after midday on Saturday if negotiators fail to reach an agreement. 

Shares of the company fell as much as 2.4 per cent Friday on the Toronto Stock Exchange. The stock was down 1.7 per cent to $33.97 as of 11:08 a.m. Toronto time, the lowest price since Aug. 29.

The impasse has created newfound uncertainty for First Quantum’s largest asset six months after the Vancouver-based company reached a tentative tax agreement with the Panamanian government to keep Cobre Panama open. The mine is an economic engine for the Central American country that accounts for about 1.5 per cent of global copper production.

Wage talks are approaching a deadline just as lawmakers in Panama consider a new operating deal brokered by the government and the company. Deliberations in Panama’s congress on the tax agreement have spurred street protests in the capital this week, according to local press reports.